Process of manufacturing triaryl phosphates



Patented Jan. 12, 1 932 u mj STATES PATENT QFFICE .wIiiL'r 3x15330381, or NITRO, WEST VIRGINIA, ASSIGNOR ro THE R'UBBER- SERVICE LABORATORIES co, or AKRON, OHIO, A. CORPORATION or onro PROCESS (IF, MANUFACTURING TRIARYL PHOSPHATES No Drawing;

This inventionrclatesto the manufacture of triaryl phosphates and has for its object to provide an improved process whereby these aryl esters may be. produced in a state 3: of high purity and in an economical and ellicient manner- More specifically, the present invention relates to the preparation of triaryl phosphates by an improved process whereby phosphorus oxychloride is reacted with a phenol in the presence of ultra violet light rays as a catalyst alone or as a component of a so-called' mixed catalyst.

Heretoilore, inthe preparation of a triaryl phosphate by the reaction between aphenol I6 and phosphorus oxychloride, the action was carriedont in-theabsenee of a catalyst, thereby requiring a long heating period at rela-- tively high temperatures for the. completion offthe reaction or in the presence of the '20 halides of metalssuch, for example, as the chlorides. o.- magnesium, calcium, aluminum iron, chromium and zinc.

It is now proposed, accordingto the pres entiirivention, to prepare a triaryl phosphate by reactingfphosphorus.oxychloride and a phenol while exposing; the mixturev to ultra violet lightaloneas a catalyst or in conjunction with other materials as a mixed catalyst.

from the following examples.

fine. of the preferred class of compounds, 'for example triphenyl phosphate, was prepared in the following-manner whereby a. material was obtained which had aphenol content of lessith-an 0.01%, 10 grams of which 7 did not decolorize '10 c; c. of of N/100 potassium permanganate. solution in forty-five minutes, and which had a corrected melting pointhigher than 501 C. or substantially between 503C. and 507 C.

Approximately three molar. portions 282 7 parts) of phenol and somewhat more t an onemolar portion (for example 160 parts) of phosphorus oxychloride were placed in a reactor suitably equipped to transmit ultra 1 violet light and heated preferably for approximately 15 to 30 hours with agitation under the influence of ultra violet light rays at a temperature of preferably approximate- 5 ly 150 to 200 C. The triphenyl phosphate Theinvention will be fully understood Application filed November 26, 1928. Serial No. 822,102.

formed was: isolated from the reaction product by distillation at reduced pressure. If preferable, however, the crude triphenyl phosphate may be isolated from the reaction product by crystallization from an organic solvent, for example xylene. The crude product was purified by any of the convenient methods of purification, for example by redistillation or recrystallization. Preferably, however, the crude triphenyl phosphate was redistilled at reduced pressure. The triphenyl phosphate thus prepared was obtained in nearly theoretical yield and of a high degree of purity. Other methods of further purification of the preferred product may be employed as hereinafter. disclosed.

Another of the preferred methods or preparinfl triaryl phosphates from phosphorus oxychloride and a phenol comprises their reaction in the presence of a mixed catalyst- Thus, approximately three molar portions (282 parts.) of phenol and somewhat more than one molar portion (for example 160' parts) of phosphorus oxychloride were placed ina reactor equipped with means. to transmit: ultra violet light to which was added substantially 0.1 to 5.0 parts of aluminum, preferably in the form of powder shavings and the like, and the mixture heated preferably at approximately 150" to 200 C. for about 15 to 30 hours with a itation under the influence of ultra violet light. On isolating the crude triphenyl phosphate formed preferably by distilling at reduced pressure, an exceptionally pure product was obtained in high yield. If convenient or desirable, however, other methods of isolating the tri phenyl phosphate from the reaction product may be. employed-1.. Thus, the material may be allowed to crystallize from an organic solvent, for example xylene.

Further, it has been found that iodine either alone or in conjunction with ultra violet light constitutes an important cata lyst for the. preparation of triaryl' phospllrate- Thus, approximately three molar portions (282 parts) of phenol and some what more than one molar portion @160 parts) of phosphorus oxychloride were placed in a reactor equipped to transmit ultra violet light. Approximately one to five parts of iodine were added to the phenolphosphorus oxychloride mixture which was then heated for about 15 to hours at a temperature preferably of substantially 150 to 200 C. with agitation under'the influence of ultra violet light. The method thus described, on isolation of the triaryl phosphate obtained by any of the convenient methods, for example by distilling the crude reaction product at a pressure below atmospheric pressure, produced a high yield of. high grade material. 7

Another method for the preparation of the preferred type of compounds comprises the reaction between ortho phosphoric acid or its alkali metallic salts and halogen ring subv stituted benzene compounds. Thus, tripotassium' phosphate was reacted with brom-' benzene preferably under. pressures higher than atmospheric pressure in the presence of a catalyst comprising cuprous chloride,.me-

talli'c copper and ultra violet light to form the desired triphenyl.phosphate, whichwas isolated in the manner previously described.

Other phenols, for example cresol, react with phosphorus:oxychloride' in the manner illustrated in the examples hereinbeforef v perature of from 150 .to 200 C. in the presgiven to formtriaryl phosphates. If convenient or desirable, the triaryl phosphate .preparedaccording to the manner. hereinbefore described may be-further puri fied according to the following methods:

, (a) Triphenyl phosphate is preferably recrystallized from an organic solvent, for examplerxylene', and then washed at a temper-' ature of 059 (lwith an alkali solution, for

examplesodi-um carbonate solution. Thus,

substantially .1000 parts of triphenyl phosphate recrystallized as described is suspended in about lOOOparts of water containing ape proximately 20-partsof sodium carbonate .at a temperature of approximately 0 to 55 C. and agitated .for about one hour. Thetriphenylephosphate was then filtered off and dried,

(6) Approximately 400 parts of triphenyl vof water containing substantially 100 parts of a dilute oxidizing solution, for example 3% sion was agitatedfor about one hourat room temperature, after which it was filtered and recrystallized from an organic solvent, for

examplexylol.

(0) Approximately 4L00parts of triphenyl phosphate wereadded to about 2000 parts of I water containing approximately 20 parts; of dissolved borax. tated for about one hour at room temperature, after which the triphenyl phosphate was filtered off andrecrystallized from an organic solvent, for example xylol. 4

f (d) Approx'mately 500 parts of triphenyl phosphate were distilled in the presence of The suspension was i agi tion. It was thendissolved in an organic sol vent, for example toluene," substantially 10 parts, of litharge added and the suspension allowed to stand for approximately 24 to 36 hours at 6 0. C. Thelitharge wasthen filtered oif and the triphenylphosphate allowed to crystallize, after which it wasfiltered off and dried. 1 V

The invention described. is not limited to the. exact temperatures, proportions and the like hereinbefore set forth-but is limited sole- 1y by the claims attachedhereto as part of i this specification.

What is claimed is:

' 1. A process for the manufacture ofa triaryl phosphate comprising the reaction between approximately three molar portions of a phenol and approximately one'molar portion of phosphorus oxychloride at a temonce of ultra violet light rays. I

.2. A process for the manufactureof a triaryl phosphate comprising. the reaction "between approximately three molar: portions of a phenol and approximately one molar portion of phosphorus oxychloride at a temperature of from 150to 200. C. in the presence of ultra violet lightrays and aluminum asa catalyst V V v 8.; A process for the manufacture of triphenyl phosphate. comprising. the. reaction between approximately threermolar portions of phenol and approximately one molar portion of phosphorus oxychloride at-a temperature of from;l 50 to.200 C.- in the presence of ultra violet light rays. I

4. A process for the manufacture of triphenyl phosphate comprising the reaction between approximately'three molar portions of'phenol and approximately one molar portion of phosphorusoxychloride at a temperature of fromol50 to 200 C. in the presence of ultra violet lightand aluminum as a catalyst. q f

In testimony whereof I hereunto afiix my signature. I r

' u WVILLIAM P. m HORST. 

